Process for the recovery of copper from porphyry ores and the like.



5 Experiments with a view to simplifying UNITED. STATES PATENT our-Ion;

enone' scnnnrnnn; or LAUENSTEIN, GERMANY, ASSIGNOR To OSCAR KRAUTH, or

- ICHARLOTTENBURG, :enussm, GERMANY.

PROCESS FOR THE RECOVERY OF COPPER FROM PORPHYRY ORES AND THE LIKE.

No Drawing.

Specification of Letters Patent. Application fi1ed April21, 1910.

Patented Mar. 14, 19 11. Serial No. 556,894.

To all whom it may concern."

Be it known that I, GEoRo SCHNEIDER, a citizen of Saxony, residing at Lauenstein, in the Kingdom of Saxony, Germany, have 5 invented new'and useful Improvements in Processes'for the Recovery of Copper from Porphyry Ores and the Like, of which the following is a specification.

Copper sul fid ores naturally rich in copper 0 or enriched by concentration are nearly exclusively worked up by the smelting process. Low grade copper-ores containing free copper sulfid if they arenot suitable for concentration and thc smelting process, .are worked up by a wet-process either by lixiviation with iron chlorids (tadt-berge proc ess) or iron sulfates (Rio Tinto). The roasted pyrites containing small quantities of copper, as produced in the manufacture 20 of sulfuric acid, are roasted with sodium chlorid, lixiviated and afterward treated with metallic iron for precipitating the copper in solution. Other methods for extracting copper from low grade ores have not -proved profitable. Those processes are well known andhave been-worked in practice foralong time. Up to the present the process consistingin the chlorinationof copper by roasting the ore with alkali ohlorids and the extraction of copper with weak hydrochloric acid followed by" the precipitation of the copper by means of metallic iron has only been applied for the treatment 0f*roasted copper bearing pyritcs but not for the ex- 5 traction of copper from crude sulfid ores such as porphyry ores. There was a general mentioned that owing to the very small opinion that such process could only be ap amount of copper remaining in the residue plied with profit to roasted copper bearing which may be considered as a loss, the procpyrites', the previous formation of iron, suless' allows the profitable working up of 40 fate and the presence of iron monosulfid copper ores containing even as little as 1% 95 being considered an absolute necessity for of copper whereas up to the present 1.5%, the formation of cupric chlorid -(see of copper appeare to be the lowest limit Schanbel, Handbook of Metallurgy II. edifor the profitable application of any copper tion, volume I, page 311). extracting method.

If the ore contains precious metals, the 100 silver goes into solution by lixiviation with a porphyric matrix. It was.found in practice that if for example a porphyry ore con taming 2.34% copper and 2.36% sulfur after breaking up bemixed with say, 10%

of sodium chlorid and heated for abOut'IO minutes at a slight dark red heat while the mass is continually stirred and the heated mass be afterward treated for about 8 hours.

at 50- C. with dilute hydrochloric acid (eon-I f taming about. 5% H01), 2.22% of copper could be obtained, whereas only 0.12% remained in the residue. In another sample which was broken 'up more finely and treated in'the same manner the residue only contained 0.05% of copper. I found that those surprisingly good results were due to the presence of silica in the ore. By chlorinating the copper in those siliciferous sulfid ores the silicic acid acts in the same way as the sulfuric-acid produced by roasting pyrites, '75 inasmuch as it decomposes the alkali chlo rids, driving out the chlorin and chlorinat-' ing the copper sulfid. That novel applica-" tion of the dry chlorination process forms i an important improvement in the art and especially in the process of working up porphyry ores or similar low. grade copper ores'containing silica, but little or no iron pyrites, because one can dispense with the, 'very expensive apparatus required for con-.

centrating low grade ores and smelting the copper from the concentrates; moreover the recovery of copper by this new process in place of concentrating and smelting the ore is considerably cheaper. Finally it maybe and chcapening the working up of porphyry ores or similar low grade copper ores proved that contrary to the statements in metallurgical handbooks the chlorination process could be worked with profit with those ores without their undergoing a previous roast-' ing. lorphyry ores are found principally in Utah and Nevada and may be described as orescontaining from 1 to 3% of copper as copper sulfid which is disseminated in hydrochloric acid whence it can be precipitated by methods well known to metallurgists. Gold can be extracted from the residue by chloringas or an acidified solution of bleaching powder.

While "silver chlorid is not soluble in hydrochloric acid, nevertheless, when the copper-chlorid and silver chlorid have completcly gone into solution the weak hydroing copper from porphyry ores and the like chloric acid acts on the residue for cxtract- I ing all the cuprous chlorid and copper oxid. The residual liquors remaining after the precipitation of copper with iron and which contain iron chlorids and alkali chloride are used for dissolving the silver, and despite the presence of chloride in excess, the silver is dissolved.

I claim The herein described method of extractcontalning copper sulfid' and silica but little or no pyrites, which method consists in breaking up the ore and mixing the same with approximately ten percentum of alkali chlorids, heating the mass at a-temperatur: not exceeding dark redness, stirring the mass during treatment, treating the mass at approximately 50 C. with dilute hydrochloric acid containing about 5% H01, and finally prel'ipitating the copper with metallic iron, without roasting the ores pre GEORG SCHNEIDER.

'liminary to treatment thereof.

Witnesses :v

FRIEDRICH EMIL EMMERIOII, J osnr REIFNER. 

